Intelligent people make their decisions based on opportunity costs. It is your alternatives that matter. Many people focus solely on what they stand to gain by choosing an option and forget to factor in what they stand to lose by forgoing another. But the ability to size up these costs is one of the things that separates great decision-makers from the rest. > THE 3-LENS PRINCIPLE: View opportunity costs through these three lenses: (1) Compared with what? (2) And then what? (3) At the expense of what?